The Ford part numbering system is easy to decode once you understand the format. All of the letters and numbers mean something; it's not just an assigned number. There are three basic sections of a Ford part number: the prefix, the basic part number, and the suffix. Each one of these sections can be broken down and decoded. For example, a trunk weatherstrip: D0AZ-6543720-A. The prefix is D0AZ, the basic part number is 6543720, and the suffix is A. To decode the prefix, D0AZ, the first letter represents the decade of the part; in this case D is the 70's. The letter A is used for the 40's, the letter B for the 50's, C for the 60's, D for the 70's, E for the 80's, and F for the 90's.
The second number in the prefix, 0 in our example, represents the year of the part. In our example, D0 is 1970. If we were looking at a 1973 part, it would be D3.
The next two letters, AZ, specify the car line that the part was initially intended for use on. In many cases the part is used on other vehicles and other cars lines. AZ stands for the full sized Ford. Codes of some of the other car lines: OZ - Fairlane/Torino, ZZ - Mustang, DZ - Falcon/Maverick, SZ - Thunderbird, TZ - Truck, MY - Full sized Mercury, GY - Comet, VY - Lincoln, and WY - Cougar.
The second section of the Ford part number is the basic part number. Parts that have to do with the body of the car will have the body code at the beginning of the basic part number, as in our example, 6543720. 65 is the body code part of the basic number which specifies hardtop. Other body code designations are as follows: 54 - 4 door sedan, 62 - 2 door sedan, 63 - fastback, 71 - station wagon, 76 - convertible, 55 - 4 door hardtop, and 66 - Ranchero. 97 is used for Ranchero as well.
The third part of the basic part number specifies the type of part, as in 43720, which is the basic number for a trunk weatherstrip. Ford uses part type groups. 1000 is wheels, hubs and drums, 2000 brakes, 3000 front suspension, 4000 rear axle, 5000 frame, exhaust and rear springs, 6000 engine parts, 7000 transmission and clutch, 8000 cooling system, 9000 fuel system, and so on. In our example, trunk weatherstrip D0AZ-6543720-A, is in group 40000 which is luggage compartment and rear end.
Lastly the suffix letter A is known as "the level of change", which means the first time the part was made it was given an A at the end. The first revision, the part was given the letter B, and so on. The suffix can also refer to the color or finish of the part, or the left or right hand use of a part. In most cases if the part is for left hand use, the basic number ends in a odd number and the right hand part ends in a even number. For example, the 1969 Mustang front fender wheel house molding. C9ZZ-16038-A is the right hand molding, and C9ZZ-16039-A is the left hand molding. Notice there is no body code in front of the basic number 16038. The reason for this is that a change in body style did not effect the application of this part.
So, that is the short and sweet of the Ford part numbering system. Once you get familiar with the grouping of these numbers you can look at a Ford part number and know what it is and what it's original intended use was.
One more thing... The number you see cast into or stamped on a part is not a Ford part number. Strange, huh? This is known as a casting number or engineering number, not a Ford part number. It may be close to the actual part number but is never the same as a Ford part number. These numbers were used in the manufacturing of the part, and that is a completely different story, although the engineering numbers follow the same type of numbering system and format. Codes, basic part numbers, and suffix are different for casting numbers.